Power disconnection apparatus for soft-shell li ion battery

ABSTRACT

A power disconnection apparatus includes a soft-shell Li ion battery and a power disconnection device. The soft-shell Li ion battery includes anode pin and a cathode pin and a soft shell enclosing the soft-shell Li ion battery. The power disconnection device includes a panel attaching to the surface of the shell of the soft-shell Li ion battery and a separation unit arranged at topside of the panel and corresponding to one of the anode pin and the cathode pin. The shell has expansion when the soft-shell Li ion battery is over-charged and the panel is move away from the soft-shell Li ion battery. Therefore, the separation unit disconnects power to the anode pin or the cathode pin.

This application is a divisional application of U.S. patent applicationSer. No. 12/046,669, filed on Mar. 16, 2008.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a power disconnection apparatus,especially to a power disconnection apparatus for soft-shell Li ionbattery.

2. Description of Prior Art

High-capacity battery becomes increasingly important as the prevailingof mobile electronic device. More particularly, lithium ion (Li-ion)battery using lithium transition metal as anode and carbon material ascathode is under extensive research.

However, the Li-ion battery is subjected to an over-charge problem whenexcessive Li ion is extracted from anode and lithium metal isprecipitated due to insertion of Li ion at cathode. Unstable peroxide isgenerated at anode, which loses lithium ion. The organic solvent in theelectrolyte has decomposition reaction when the over-charge voltage isabove a voltage threshold. Moreover, lots of flammable gas is alsogenerated. The battery has abnormal heating due to rush heat generation,which induces risk of battery damage.

The applicant of the subject application has proposed various protectivemechanisms for charging battery, for example, Taiwan Utility ModelTWM292169 and TWM275625. More particularly, Taiwan Utility ModelTWM292169 discloses a protection apparatus for Li-ion battery. Theprotection apparatus for Li-ion battery comprises an abnormalitydetection circuit and a photo-coupling circuit. The abnormalitydetection circuit examines the voltage of the rechargeable battery andoutputs a detection signal. The photo-coupling circuit is electricallyconnected to the abnormality detection circuit and adjusts an impedancethereof according to the detection signal output from the abnormalitydetection circuit. The connection between the rechargeable battery andan external circuit is opened or close for discharging or charging therechargeable battery. The Taiwan Utility Model TWM275625 also disclosesa protection apparatus for rechargeable battery. The protectionapparatus for rechargeable battery mainly comprises a first protectionloop and a second protection loop. The first protection loop comprises amain current load connected to a main circuit and a battery, and athermo-coupler switch connected to the battery and the main circuit. Thesecond protection loop comprises a protection circuit and a heater. Theprotection circuit is connected to the main circuit and senses thebattery voltage for generating a start signal. The heater is connectedto the protection circuit and is activated by the thermo coupler switch.Moreover, the mechanical protection apparatus for cylindrical hard-shellLi ion battery activates a blow-off valve when the internal pressure isincreased due to excessive charging of batter. A conductive pin isbroken by the operation of the blow-off valve to provide protection.

The above-mentioned protection mechanism for Li ion battery can providelimited protection for over-charged Li ion battery. However, theabove-mentioned protection mechanism has risk of damaging components ofbattery after long time use. The mechanical protection mechanism for thecylindrical hard-shell Li ion battery cannot be used for soft-shell Liion battery. Moreover, the above-mentioned protection mechanism hascomplicated components. It is desirable to provide a protectionmechanism for Li ion battery with simple structure and with no harm tothe components of the Li ion battery.

SUMMARY OF THE INVENTION

It is the object of the present invention to provide a powerdisconnection apparatus for a soft-shell Li ion battery, wherein aseparation unit is arranged with respect to the pins of the soft-shellLi ion battery. The volume expansion of soft-shell Li ion battery afterheating is exploited to disconnect power delivered to the pin by theseparation unit. The structure for the protection mechanism issimplified with lower cot and the explosion of soft-shell Li ion batterycan also be prevented.

Accordingly, the present invention provides a power disconnectionapparatus for a soft-shell Li ion battery. The power disconnectionapparatus comprises a soft-shell Li ion battery and a powerdisconnection device. The soft-shell Li ion battery includes anode pinand a cathode pin and a soft shell enclosing the soft-shell Li ionbattery. The power disconnection device includes a panel attaching tothe surface of the shell of the soft-shell Li ion battery and aseparation unit arranged at topside of the panel and corresponding toone of the anode pin and the cathode pin. The shell has expansion whenthe soft-shell Li ion battery is over-charged and the panel is move awayfrom the soft-shell Li ion battery. Therefore, the separation unitdisconnects power to the anode pin or the cathode pin.

BRIEF DESCRIPTION OF DRAWING

The features of the invention believed to be novel are set forth withparticularity in the appended claims. The invention itself however maybe best understood by reference to the following detailed description ofthe invention, which describes certain exemplary embodiments of theinvention, taken in conjunction with the accompanying drawings in which:

FIG. 1 is an exploded view of the present invention.

FIG. 2 is a perspective view of the present invention.

FIG. 3 is a top view of the present invention.

FIG. 4 is a sectional view of the present invention used for batteries.

FIG. 5 is a sectional view showing the state after batteries areover-charged.

FIG. 6 is a partially enlarged view of the portion A in FIG. 5.

FIG. 7 is the sectional view of another preferred embodiment of thepresent invention.

FIG. 8 is the sectional view showing the operation status in FIG. 7.

DETAILED DESCRIPTION OF THE INVENTION

With reference to FIGS. 1 to 3, the power disconnection apparatusaccording to the present invention comprises a soft-shell Li ion batteryand a power disconnection device.

The soft-shell Li ion battery 1 comprises a plurality of anode platesand cathode plates and isolation film (not shown) sandwiched between theanode plates and cathode plates. A soft shell 11 encloses the anodeplates, the cathode plates and the isolation film, which is, forexample, an aluminum foil or foil of other metal. An anode pin 12 and acathode pin 13 are connected to the topside of the soft-shell Li ionbattery 1, respectively. The anode pin 12 comprises an anode leg 121connected to each of the anode plates and an anode flange 122 connectedto one end of the anode leg 121. The anode leg 121 can be made ofaluminum foil. The cathode pin 13 comprises a cathode leg 131 connectedto each of the cathode plates and a cathode flange 132 connected to oneend of the cathode leg 131. The cathode leg 131 can be made of copperfoil.

The power disconnection device 2 comprises a panel 21 attached to theshell 11 of the soft-shell Li ion battery 1 and a separation unit 22connected to the topside of the panel 21 and corresponding to the anodepin 12. The panel 21 is a rigid plate made of plastic material or othermaterial. The separation unit 22 comprises a cutting knife 221 and twofixing arms 222 extended vertically from both sides of the cutting knife221. The cutting knife 221 and the panel 21 are formed on opposite sideswith respect to the anode pin 12; and the fixing arms 222 are connectedto the panel 21. The cutting knife 221 comprises continuous teeth 223 onthe side facing the anode pin 12 and used to cut the anode leg 121 ofthe anode pin 12. Moreover, the separation unit 22 can also be arrangedwith respect to the cathode leg 131 to achieve the similar effect.

With reference to FIGS. 4 to 6, the power disconnection device 2 can beused for the battery set composed of multiple soft-shell Li ionbatteries 1 in serial connection or parallel connection, besides theapplication to a single soft-shell Li ion battery 1. When the soft-shellLi ion battery 1 is excessively charged, the casing 11 has volumeexpansion. The panel 21 is moved away from the soft-shell Li ion battery1 and the separation unit 22 cuts the anode leg 121 of the anode pin 12to disconnect the electrical power. In ordinary use, the casing 11 hassurface expansion when the soft-shell Li ion battery 1 is excessivelycharged. The panel 21 has about 2 mm lateral displacement, which issufficient to cut the anode leg 121 by the cutting knife 221. Therefore,the safety for charging the soft-shell Li ion battery 1 is enhanced.

With reference to FIGS. 7 and 8, in another preferred embodiment of thepresent invention, a through hole 123 is defined on the anode flange 122of the anode pin 12 and V-shaped groove 124 is formed atop the throughhole 123. An aperture 211 is defined on the panel 21 of the powerdisconnection device. The separation unit 22 is of plate shape andopenings 224 are defined at topside and bottom side thereof. Fixingelement such as rivet passes through the through hole 123 and theopenings 224, whereby both ends of the separation unit 22 are fixed tothe anode flange 122 and the panel 21, respectively. The shell 11 hasvolume expansion when the soft-shell Li ion battery 1 is excessivelycharged. The panel 21 is moved away from the soft-shell Li ion battery 1and the separation unit 22 cuts the anode flange 122 at the V-shapedgroove 124.

Although the present invention has been described with reference to thepreferred embodiment thereof, it will be understood that the inventionis not limited to the details thereof. Various substitutions andmodifications have suggested in the foregoing description, and otherwill occur to those of ordinary skill in the art. Therefore, all suchsubstitutions and modifications are intended to be embraced within thescope of the invention as defined in the appended claims.

1. A power disconnection apparatus for an over-charged soft-shell Li ionbattery, comprising: a soft-shell Li ion battery comprising an anode pinand a cathode pin, and a soft shell enclosing the soft-shell Li ionbattery; and a power disconnection device comprising a panel attaching asurface of the soft shell and a separation unit connected to the paneland corresponding to one of the anode pin and the cathode pin; whereinthe soft shell is expanded when the soft-shell Li ion battery isover-charged and the panel is moved away from the soft-shell Li ionbattery, whereby the separation unit disconnects power supplied to oneof the anode pin and the cathode pin, wherein the anode pin comprises ananode leg and an anode flange connected to one end of the anode leg, andwherein the anode flange of the anode pin comprises a through hole, thepanel comprises an aperture thereon and the separation unit is of plateshape with openings at both ends thereof, the anode flange and the paneland the separation unit are combined by using a rivet passing throughthe through hole, the aperture and the openings.
 2. The powerdisconnection apparatus of claim 1, wherein the shell is an aluminumfoil.
 3. The power disconnection apparatus of claim 1, wherein twoV-shaped grooves are defined atop the through hole.